• Journal of Internet Computing and Services
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• v.15 no.3
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• pp.101-107
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• 2014

With the development of online service, recent forms of databases have been changed from static database structures to dynamic stream database structures. Previous data mining techniques have been used as tools of decision making such as establishment of marketing strategies and DNA analyses. However, the capability to analyze real-time data more quickly is necessary in the recent interesting areas such as sensor network, robotics, and artificial intelligence. Landmark window-based frequent pattern mining, one of the stream mining approaches, performs mining operations with respect to parts of databases or each transaction of them, instead of all the data. In this paper, we analyze and evaluate the techniques of the well-known landmark window-based frequent pattern mining algorithms, called Lossy counting and hMiner. When Lossy counting mines frequent patterns from a set of new transactions, it performs union operations between the previous and current mining results. hMiner, which is a state-of-the-art algorithm based on the landmark window model, conducts mining operations whenever a new transaction occurs. Since hMiner extracts frequent patterns as soon as a new transaction is entered, we can obtain the latest mining results reflecting real-time information. For this reason, such algorithms are also called online mining approaches. We evaluate and compare the performance of the primitive algorithm, Lossy counting and the latest one, hMiner. As the criteria of our performance analysis, we first consider algorithms' total runtime and average processing time per transaction. In addition, to compare the efficiency of storage structures between them, their maximum memory usage is also evaluated. Lastly, we show how stably the two algorithms conduct their mining works with respect to the databases that feature gradually increasing items. With respect to the evaluation results of mining time and transaction processing, hMiner has higher speed than that of Lossy counting. Since hMiner stores candidate frequent patterns in a hash method, it can directly access candidate frequent patterns. Meanwhile, Lossy counting stores them in a lattice manner; thus, it has to search for multiple nodes in order to access the candidate frequent patterns. On the other hand, hMiner shows worse performance than that of Lossy counting in terms of maximum memory usage. hMiner should have all of the information for candidate frequent patterns to store them to hash's buckets, while Lossy counting stores them, reducing their information by using the lattice method. Since the storage of Lossy counting can share items concurrently included in multiple patterns, its memory usage is more efficient than that of hMiner. However, hMiner presents better efficiency than that of Lossy counting with respect to scalability evaluation due to the following reasons. If the number of items is increased, shared items are decreased in contrast; thereby, Lossy counting's memory efficiency is weakened. Furthermore, if the number of transactions becomes higher, its pruning effect becomes worse. From the experimental results, we can determine that the landmark window-based frequent pattern mining algorithms are suitable for real-time systems although they require a significant amount of memory. Hence, we need to improve their data structures more efficiently in order to utilize them additionally in resource-constrained environments such as WSN(Wireless sensor network).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.1
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• pp.81-88
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• 2004

Turbo code has been adopted in the 3GPP standard, since its performance is very close to the Shannon limit. However, the turbo decoder requires a lot of computations and the amount of the memory increases as the block size of turbo codes becomes larger. In order to reduce the complexity of the turbo decoder, the Log-MAP, the Max-Log-MAP and the sliding window algorithm have been proposed. In this paper, the performance of turbo codes adopted in the 3GPP standard is analyzed by using the floating point and the fixed point implementation. The efficient decoding method is also proposed. It is shown that the BER performance of the proposed method is close to that of the Log-MAP algorithm.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.112-112
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• 2009

Temperature dependence of the ferroelectric properties of poly(vinylidefluoride-trifluoroethylene) copolymer thin films are studied with various insulators such as $SrTa_2O_6$ and $La_2O_3$. Thin films of poly(vinylidene fluoridetrifluoroethylene) 75/25 copolymer were prepared by chemical solution deposition on p-Si substrate. Capacitance-voltage (C-V) and current density (J-V) behavior of the Au/P(VDF-TrFE)/Insulator/p-Si structures were studied at ($150-200\;^{\circ}C$) and dielectric constant of the each insulators were measured to be about 15 at $850\;^{\circ}C$ for 10 minutes. Memory window width at 5 V bias the MFIS(metal-ferroelectric-insulator-semiconductor) structure with as deposited films was about 0.5 V at high temperature ($200\;^{\circ}C$). And the memory window width increased as voltage increased from 1 V to 5 V.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.9-12
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• 1998

Film characteristics of thin reoxidized nitrided oxides were investigated by SIMS analysis and C-V method in order to use the gate dielectric for charge-trap type NVSMs instead of ONO stacked layers. Nitric oxide(NO) annealed film has the nitrogen content sharply peaked at the Si-SiO$_2$ interface, while it is broad for nitrous oxide($N_2$O) ambient. The nitrogen peak concentration increased with anneal temperature and time. The position of nitrogen content in the oxide layer was due to be precisely controlled. For the films annealed NO ambient at 80$0^{\circ}C$ for 30min. followed by reoxidized at 85$0^{\circ}C$, the maximum memory window of 3.5V was obtained and the program condition was +12V, 1msec for write and -l3V, 1msec for erase.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.339-343
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• 2005

Pt-$SrBi_2Nb_2O_9(SBN)-Pt-Y_2O_3-Si$ gate field effect transistors (MFMISFETs) have been fabricated and the SBN thin films are rapid thermal annealed in oxygen plasma. The grain size of the SBN becomes 4 times much larger than that of furnace annealed SBN films even at the same annealing temperature of $700^{\circ}C$, remnant polarization value of Pt-SBN-Pt is improved by 2 times. Using the rapid grain growth of SBN for the MFM-ISFET, memory window and programming characteristics of on/off states are fairly well improved.

• Transactions on Electrical and Electronic Materials
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• v.17 no.1
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• pp.25-28
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• 2016

We investigate the effect of interface states on the endurance of a charge trap flash (CTF) NOR array using charge pumping methods. The endurance test was completed from one cell selected randomly from 128 bit cells, where the memory window value after 10² program/erase (P/E) cycles decreased slightly from 2.2 V to 1.7 V. However, the memory window closure abruptly accelerated after 10³ P/E cycles or more (i.e. 0.97 V or 0.7 V) due to a degraded programming speed. On the other hand, the interface trap density (Nit) gradually increased from 3.13×10¹¹ cm⁻² for the initial state to 4×10¹² cm⁻² for 10² P/E cycles. Over 10³ P/E cycles, the Nit increased dramatically from 5.51×10¹² cm⁻² for 10³ P/E cycles to 5.79×10¹² cm⁻² for 10⁴ P/E cycles due to tunnel oxide damages. These results show good correlation between the interface traps and endurance degradation of CTF devices in actual flash cell arrays.

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.363-369
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• 2017

Phase-change random access memory (PRAM) has been emerged as a potential memory due to its excellent scalability, non-volatility, and random accessibility. But, as the cell current is reducing due to cell size scaling, the read-sensing window margin is also decreasing due to increased variation of cell performance distribution, resulting in a substantial loss of yield. To cope with this problem, a novel adaptive read-sensing reference current generation scheme is proposed, whose trimming range and resolution are adaptively controlled depending on process conditions. Performance evaluation in a 58-nm CMOS process indicated that the proposed read-sensing reference current scheme allowed the integral nonlinearity (INL) to be improved from 10.3 LSB to 2.14 LSB (79% reduction), and the differential nonlinearity (DNL) from 2.29 LSB to 0.94 LSB (59% reduction).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.119-119
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• 2008

The electrical characteristics of Metal-Ferroelectric-Nitride-Oxide-Silicon (MFNOS) structure is studied and compared to the conventional Silicon-Oixde-Nitride-Oxide-Silicon (SONOS) capacitor. The ferroelectric blocking layer is SrBiNbO (SBN with Sr/Bi ratio 1-x/2+x) with the thickness of 200 nm and is fabricated by the RF sputter. The memory windows of MFNOS and SONOS capacitors with sweep voltage from +10 V to -10 V are 6.9 V and 5.9 V, respectively. The effect of ferroelectric blocking layer and charge trapping on the memory window was discussed. The retention of MFNOS capacitor also shows the 10-years and longer retention time than that of the SONOS capacitor. The better retention properties of the MFNOS capacitor may be attributed to the charge holding effect by the polarization of ferroelectric layer.

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.257-260
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• 2001

Routing region modeling methods for PCB auto-routing system in Shape based type(non-grid method) used region process type and the shape located in memory as a individual element, and this element consumed small memory due to unique data size. In this paper we design PCB(Printed Circuit Board) auto-routing system using the auction algorithm method that 1) Could be reached by solving the shortest path from single original point to various destination, and 2) Shaped based type without any memory dissipation with the best speed. Also, the auto-routing system developed by Visual C++ in Window environment, and can be used in IBM Pentium computer or in various individual PC system.

• Journal of the Korean Society for Library and Information Science
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• v.44 no.4
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• pp.115-130
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• 2010

In the archival field, the last decade has witnessed much discussion on archives' broad responsibilities for social memory. Considering that the social role of archives has stemmed from postmodern thinking suggests a paradigm shift from viewing archives as static recorded objects to viewing them as dynamic evidence of human memory. The modern archives and archivists are products of nineteenth-century positivism, limiting their function to archiving written documents within stable organizations. The new thoughts on the social role of archives provide a chance to realize that traditional archival practices have preserved only a sliver of organizational memory, thus ignoring fluid records of human activities and memory. Archival description is the primary method for users to access materials in archives. Thus, it can determine how archival materials will be used (or not used). The traditional archival description works as the representation of archival materials and is directly projected from the hierarchy of organizational documents. This paper argues that archivists will need to redefine archival description to be more sensitive to atypical types of archival materials from various cultural contexts. This paper surveys the postmodern approaches to archival concepts in relation to descriptive practices. It also examines some issues related to representing historically marginalized groups in archival description who were previously neglected in traditional archival practices.